Development Of Portable Farm-oriented Area Measuring Apparatus Based On STM32F407 And Dual-mode Positioning Of GPS And BD

To obtain high cost performance,traditional area portable measuring apparatus usually adopts 16-bit or 32-bit MCU and GPS module.With the development of the embedded system and BD positioning technologies,It is possible to develop more rapid and accurate area measuring apparatus by using of high performance STM32 series microprocessor and GPS and BD dual-mode positioning technology.In this study,one kind of portable and farm-oriented area measuring apparatus based on STM32 and dual-mode positioning of GPS and BD was developed.Based on the general analysis of embedded systems and dual-mode positioning technologies of GPS and BD,the hardware and software platform of area measuring apparatus were selected.STM32F407 of STM32 Series MCU were used as the kernel of hardware and necessary peripheral modules were equipped.The software of the apparatus was developed based on ?C/OS-?,a real-time embedded operating system with open source code.Some equipment drivers and application program were also included in the software system.The measuring system includes two parts:the reference station and handset,the former is mainly used to calculate location errors,the latter is mainly to used to complete the area measurement.Based on ?C/OS-?,control tasks of the reference station and handset were planed firstly and the communication coordination mechanism among each task was then designed.Among them,five tasks are involved in the refer ence station:user interface management,positioning data receiving,error calculation,data communication with handset and auxiliary function;six tasks are involved in handset:user interface management,area calculation,error calculation,data communication with reference station,data storage and auxiliary function.Moreover,the realization method of area calculation was also studied.First,the reference station send error data with real-time to the handset,the handset will operation itself positioning data and error data to forming the relatively accurate WGS-84 coordinates of points.Then by Gauss transformation of the coordinates of points,plane coordinate points are generated and a plurality of planar measuring point structure into a plane polygon.Finally the handset calculate polygon area by using the Green formula.Finally,the developed measuring apparatus were tested and analyzed.Experiment results showed that the apparatus can not only access GPS and BD positioning information rapidly,but also can accurate precisely the field areas and easy to carry.lt has the broad application prospect.